Hmm. . . some surprises, some blatantly obvious. . .
My votes:
Thracian peltasts
Persian archer-spearmen
Rhaetian axemen

I only voted for 3 because the Cretan archers (#3 for me) are just blowing everything else away already and I didn't see Ethiopian swordsmen on there.

I'm a bit surprised the Thracians aren't more popular. I hire them as Getai even though I can recruit them in my cities. The Rhaetians aren't the most powerful or widely available, I just think they're kewl.